Study On Performance Improvement & EMI Of Field Emission Display

Field Emission Display (FED) is one of the cathode ray fluorescent display devices, falls into the catalogue of flat panel display (FPD). Nowadays, FEDs using nano-carbon tubes (CNT-FED) as cathode ejecting materials are the most hotspot in research field. Because CNT-FED displays by the electrons emitted by carbon nanotube to bomb phosphor, whose process is complex and hard to measure, so it is rather difficult to study its performance mechanism by experimental measurement and observation. The most usual method is to simulate the emission process of carbon nanotube by high-speed computer, which still has a long way from engineering application. Meanwhile, traditional theoretical simulation only takes into account the influence on electrical characteristics such as emission current density and electron spot determined by display device structure while seldom consider the peripheral driving system. Then it is hard to hold the CNT-FED system as a whole. Thus, this thesis tries to build an applicable equivalent circuit model for CNT-FED to analyze the FED performance mechanic and discuss the coupling noise between parallel electrodes, power consumption and waveform distortion.After the analysis and comparison to the traditional Spint-array FED equivalent circuit model, equivalent circuit models oriented to diode structure and normal-gate structure CNT-FED respectively are proposed. In this model, capacitance is considered as the core component, diode and N-MOSFET are added to present the non-linear emission characteristic during performance. Pspice is used for the simulation. From the comparison of the practical drive waveforms to the simulation results, this model has been proved as a precise and reasonable one.Coupling noise between parallel electrodes, power consumption and waveform distortion in diode structure and normal-gate structure are also studied for comparing the two different structure, so suggestion are also proposed for improvement.By studying the voltage-luminance curve of CNT-FED under the PWM method, this thesis has proved the recent video source for CRT is not fit for our CNT-FED system, thus some kind of Gamma correction should be introduced. Ordinary Gamma correction method such 10bit look-up table and error diffusion methods are introduced, and the most suitable one is discussed to improve the display performance.As the FED more and more prosperous, EMC becomes the more and more considerate aspect in the whole system. Good EMC guarantees the good performance of the whole FED system. In the view of improving the whole system's performance, discussion is made including the EMC in PCB board, the display device's capacitance effect to EMC, finally a protect circuit is proposed to avoid the flash current damage to the high voltage driver chips.